Saprobic on decaying wood of Tectonagrandis. Sexual morphHysterothecia 1400–2100 μm long, 350–500 μm high, 600–1000 μm diam. (x̄ = 1780 × 400 × 700 μm, n = 5), superficial, black, solitary to aggregated, coriaceous, smooth, elliptical or irregular in shape, elongated with a longitudinal slit. Exciple 75–115μm (x̄ = 90, n = 20) wide, composed of several layers of brown to dark brown, thick-walled cells of textura angularis. Hamathecium 2–3.5 μm wide, dense, septate pseudoparaphyses, constricted at the septum, filiform, pale-yellow pigmented, forming epithecium above the asci and enclosed in a gelatinous matrix. Asci 190–260 × 13–18 μm (x̄ = 230 × 16 μm, n = 10), 8-spored, bitunicate, clavate to cylindrical, with a short furcate pedicel, apically rounded, without a distinct ocular chamber. Ascospores 36–44 × 11–17 μm (x̄ = 41 × 13 μm, n = 30), uni-seriate, yellowish to brown, with 1–3-septa, ellipsoidal to fusiform, slightly rounded or pointed at both ends, constricted at the central septum, with granular appearance. Asexual morph Undetermined.

Bursera sp (Mexico), Heveabrasiliensis and Tectonagrandis (Thailand) (Thambugala et al. 2016; Cobos-Villagran et al. 2020; this study).

Thailand, Tak Province, Mogro District, Amphoe Umphang, on dead woods of Tectonagrandis (Lamiaceae), 20-Aug-2019, G.C. Ren, T203 (HKAS 115534), living culture MFLUCC 21-0035.

Rhytidhysteronneorufulum was introduced by Thambugala et al. (2016) based on both morphological and phylogenetic analyses of a combined dataset of LSU, SSU and tef1-α sequence data. Thambugala et al. (2016) accounted R.neorufulum (MFLUCC 13-0216) from decaying woody stems and twigs in Thailand. Our new collection shares similar morphology to that of the type description of Rhytidhysteronneorufulum (MFLUCC 13-0216) in having superficial, coriaceous, elliptical or irregular, elongated hysterothecia with a longitudinal slit, bitunicate, cylindrical, short furcate pedicel asci and yellowish to brown, ellipsoidal to fusiform ascospores with 1–3-septa (Thambugala et al. 2016). However, our new collection has larger asci (190–260 × 13–18 μm vs 185–220 × 9.5–13 μm) and ascospores (36–44 × 11–17 μm vs 19–31 × 8–13 μm) in comparison to the type of Rhytidhysteronneorufulum (MFLUCC 13-0216). The multi-gene phylogenetic analysis based on combined SSU, LSU, ITS, and tef1-α sequence data showed that our collection is related to Rhytidhysteronneorufulum (Figure 1).